Drake



Aug. 11, 1959 R. s. DRAKE 2,$99,487

INSULATORS FOR SUPPORTING AN ELECTRIC WIRE FENCE Filed May 8, 1956 2 Sheets-Sheet 1 a I fODI/Ey S UI'TLEUMTH .DKHKE,

v IN VE V TO/Q Aug. 11, 1959 s, DRAKE 2,899,487

INSULATORS FOR SUPPORTING AN ELECTRIC WIRE FENCE Filed May 8, 1956 2 Sheets-Sheet 2 KDDNE r Swrrwwmn/ ZDAWKE;

United States Patent INSULATORS FOR SUPPORTING AN ELECTRIC WIRE FENCE Rodney Shuttleworth Drake, Birmingham, England Application May 8, 1956, Serial No. 583,465

Claims priority, application Great Britain May 11, 1955 2 Claims. (Cl. 174-170) This invention relates to insulators which are used for supporting an electric wire fence. Such insulators often consist of metal ground posts having spiked lower ends adapted to be forced into the ground, and they are usually provided with at least one insulator for the wire fence. This insulator may be provided on the post itself, as provided for in British Letters Patent No. 724,049, or the insulator may be assembled to the post as by mounting the insulator on a metal clip or clamp which detachably engages the post. Alternatively, the insulator may be combined with a metal screw to engage a wooden upright, post or other fixture available on farming land.

I have been producing a pig-tail insulator in which an end of a metal rod of round cross-section is bent into an open eye or loop and a flexible insulating sleeve, made of polyvinyl chloride, rubber or like flexible material, is sleeved over the eye or loop so that when an electric wire fence is inserted therein, it is insulated from the metal rod. A serious drawback has been discovered in that in the course of practical use, the insulator becomes ineffective consequent upon the wire fence rubbing and eventually cutting into the sleeve either as a result of the tension on the wire or the effect of wind pressure on it, or due to both of these conditions. It will be appreciated, therefore, that when such an insulator fails, a dangerous condition may arise which is not easy to detect especially where a substantial area is protected by an electric wire fence.

The primary object of the present invention is to provide a thermoplastic insulator for an electric wire fence, which is simple, inexpensive and durable, and is capable of preventing the wire fence from coming into contact with the conductor mounting the insulator even when the insulator may become worn due to the above condition arising.

According to the present invention an insulator for supporting an electric wire fence comprises a metal mount, such as a ground post and an insulator having an open eye or loop for reception of the fence, one end of the insulator being sleeved over the mount and secured thereto while the insulator was in a plastic state.

The term insulator used in this specification means a rod or sleeve made of normally rigid thermoplastic material which when heated can be worked into a desired shape that is retained at normal winter and summer tem peratures.

According to another aspect of the invention an insulator for an electric wire fence consists of a metal member of round section on an end of which a tube of normally rigid thermoplastic material is sleeved and rigidly attached thereto, the remaining part of the tube remote from the point of attachment being formed into an open eye or loop, for reception of the wire fence.

Preferably, the thermoplastic sleeve is mechanically pressed into intimate contact with the mount. For this purpose the metal mount is formed with keying means.

The manufacture of an insulator, according to the invention for an electric wire fence, will now be described 2,899,487 Patented Aug. 11, 1959 by way of example with reference to the accompanying drawings wherein:

Fig. 1 is a perspective view of heating equipment for use in softening thermoplastic sleeves in preparation for working them into insulators on metal ground posts or metal mountings.

Fig. 2 is a plan view of equipment used in assembling the sleeves on the ground posts or mountings and forming them with loops of the pigtail type.

Fig. 3 is a plan view similar to Fig. 2 illustrating the completion of the assembling and forming operations of the sleeve on a metal post or mounting.

Fig. 4 is an elevation of a spigot, seen in Figs. 2 and 3, used when bending the sleeves into pigtail loops.

Fig. 5 is a sectional elevation of an insulated ground post made according to the invention.

Fig. 6 is a view similar to Fig. 5 but modified by substituting a mounting screw for the ground post.

As will be seen from Fig. 1 of the drawings, there is provided a disc member 1 which is rotatable about a generally vertical axis 2, the member 1 mounting at its perimeter several radial rods 3 of round section on which thermoplastic sleeves 4 are threaded. The sleeves 4 may be made of commercial polyvinyl chloride which is rigid or slightly flexible at winter and summer normal temperatures, and which when heated becomes easily workable for bending into predetermined shapes that are rendered permanent on cooling. These sleeves 4 can be rendered flexible for working by bringing them into a heat zone 5 of an electrical heater 6 by intermittently or continuously rotating the axis 2 by any driving means.

At a take-off position 7, these flexible sleeves 4 are individually removed by an operator and sleeved over an end 8 of a ground post 9 formed with an annular keying groove 10 having transverse ribs 10a and being provided at the other end with a spike 11.

As will be seen at Figs. 2 and 3, a vice equipment 12 is provided for attaching the sleeve 4 to the end 8 and for manipulating it into a pigtail loop 13 for reception of an electric wire fence (not shown). The vice equip= ment 12 has a fixed jaw 14 and a movable jaw 15, and grooved jaw plates 16. Support and clamp means 17, 18 are provided for receiving and holding the post 9 in a horizontal plane between the open jaws 14, 15. The vice has a stop 19 which is turnable on an axis 20, arranged on the right hand side of the vice for positioning the end 8 of the post 9 relative to the vice jaws 14, 15 preparatory to the closing of the latter. The movable jaw 15 has fast with it an upright spigot 21 of round section formed on the exterior with a spiral groove 22, which serves as a former for shaping the sleeve 4 into a predetermined shape of the pigtail loop 13. The fixed jaw 14 carries a fixed abutment 23 having an inclined forward edge 24 which is adapted to form an abutment by which the free end 25 of the pigtail loop 13 is held in a required position after it has been formed on the spigot 21. Combined with the vice equipment 12 is a double acting air cylinder 26 having a delivery pipe 27, a tap 23, and two branches 29, 30, the extremities of the latter being directed in predetermined positions for the purpose of directing blasts of cooling air from the cylinder 26 on the pigtail loop 13 and its anchorage to the end 8 of the post 9.

A method of making an insulator for an electric wire fence with the equipment above described is as follows:

Sleeves 4 made of polyvinyl chloride and of a predetermined length are threaded on the rods 3, the disc 1 is caused to rotate at a slow speed so as to bring each sleeve into the heat zone 5 for a sufficient time interval to render the sleeve plastic. An operator takes a post 9 and feeds its end 8 up to the stop 19, the other end being supported in the rest 17 and the intermediate part 3 being held by the clamp 18 in response to an operation of the cylinder 26.

The operator moves the stop 19 clear of the end 8 and taking a heated sleeve 4 pushes it over the said end. The air operated clamp 18 is then released by any suitable means, the sleeved portion of the post 9 is slid between the jaw plates 16 and the vice jaw 15 is closed under pressure thereby to press the sleeve 4 into the jaw plates 16 and cause the plastic material to flow into the keying grooves 10. The operator now bends the free part of the sleeve 4 around the spiral groove 22 on the spigot 21 up to the inclined edge 24 of the abutment 23, thus forming the pigtail loop 13. The plastic material is cooled either atmospherically or by a blast of cold air. In the latter case, by turning the tap 28 into the on position blasts of cooling air from the cylinder 26 can be delivered by the branch 30 onto the pigtail 13 and by the branch 29 (which may be flexible) on the portion which has been pressed on the post 9; the thermoplastic insulator loop 13 and the sleeved connection to the post 9 remote from the loop are now restored to the former rigid state. All these operations can be carried out quickly and easily by an ordinary intelligent person.

It will be appreciated that the operation of pressing the sleeve 4 on to the end 8 is the simplest form of the invention, but obviously it is possible to substitute a rod of thermoplastic material, one end of which is formed with a socket end.

It will also be appreciated that the pigtail loop 13 may be preformed in a separate operation prior to heating the sleeve, engaging it with the end 8 and finally pressing it into intimate contact therewith; the method of production I have described, however, is the simplest and easiest to perform in one operation.

An important advantage to be secured by the invention is that the loop 13 while carried by the post is separated from it, so that when an electric wire fence is engaged in the loop it cannot under ordinary use come into contact with the post and make it live in the event of wear taking place on the loop as above referred to.

Instead of applying the invention to the post 9, it can be applied equally well to a metal rod (Fig. 6) one end of which is threaded at 32 for engagement with a timber post, tree or the like, the other end being provided with a head 33 and a neck or keying groove 10 having transverse ribs 10a as previously referred to.

I claim:

1. An insulator for an electric fence wire, comprising a metal member having a substantially cylindrical end with a keying means therein and an open pigtail portion for receiving the wire, the cylindrical end having an annular keying groove with a plurality of ribs being provided transversely of said groove, said pigtail portion being a sleeve of thermoplastic material which is practically rigid at normal temperatures, an end of the sleeve remote from the pigtail being in tight engagement with the cylindrical end of the metal member and its keying means whereby the metal member and the open pigtail portion are securely fastened together.

2. An insulator for an electric fence wire, comprising a metal member having a substantially cylindrical end with a keying means therein and an open pigtail portion for receiving the wire, the cylindrical end having an annular keying groove with a plurality of ribs being provided transversely of said grooves, said pigtail portion consisting of thermoplastic material which is practically rigid at normal temperatures and being constituted by a rod with a tubular end remote from the pigtail, said tubular end fitting tightly over the cylindrical end of the metal member and its keying means whereby the metal member and the open pigtail portion are securely fastened together.

References Cited in the file of this patent UNITED STATES PATENTS 2,437,344 Behlmann Mar. 9, 1948 2,451,530 Beard Oct. 19, 1948 2,577,466 Jones Dec. 4, 1951 2,751,629 Dick June 26, 1956 2,791,625 Swanson May 7, 1957 FOREIGN PATENTS 539,317 Great Britain Sept. 4, 1941 

